The present invention relates generally to methods and apparatus for removing magnetic particles and substances from non-magnetic material. More specifically, the present invention relates to method and apparatus for removing magnetic contaminants from reclaimed rubber.
Devices for separating magnetic substances from loose, non-magnetic material have been suggested in the past. These devices generally include magnetic elements which attract and capture magnetic particles carried by the material. One such device is illustrated in U.S. Pat. No. 2,912,106 issued to Martin. The magnetic separator described in this patent includes a collection assembly in which a series of V-shaped prongs are spatially distributed. At least one permanent magnet is pivotally mounted to a side wall of the collection assembly and serves to magnetize the prongs when pivoted to a position immediately adjacent the ends of the prongs. After the material has passed through the collection assembly, a slide is inserted into the housing to close off the outlet and the magnet is pivoted outwardly so that magnetism is no longer induced in the prongs. The collection assembly is then cleaned of the released magnetic particles.
Although the Martin devices work very effectively, the processing of material must be interrupted periodically in order to clean the collection assembly. For this reason alternative devices are desirable for dealing with large volume material flows.
Magnetic separators for continuously separating magnetic substances from loose material have also been suggested, but none have proved totally effective.
One prior suggested magnetic separator includes a conveyor belt reeved around a magnetic pulley. Material is carried by the belt over the pulley. The non-magnetic ingredients fall downwardly off the belt and are collected by a suitable container. The magnetic constituents of the material adhere to the belt under the influence of the magnetic pulley and are carried around the pulley to a discharge station where the magnetic material is released and drops into a separate collecting receptacle.
Another known apparatus includes a rotating drum having a magnetized portion. In operation, material is allowed to cascade over the rotating drum. The non-magnetic components of the material are not influenced by the drum and thus can drop freely into a receptacle or onto another conveyor positioned below the drum. The magnetic constituents however adhere to the drum until it passes beyond the magnetized portion where it then drops into a separate receptacle.
Magnetic separators have also been suggested which include an endless conveyor that transports magnetic elements through the material. These elements are generally magnetized by a stationary magnet when they are passing through the material and thus attract the magnetic particles carried therein. The elements carry the captured particles to a discharge location. The separating efficiency of these suggested devices have not been totally satisfactory to date.
With the advent of steel belted tires, the problem of removing the steel cords in order to reclaim the rubber from these tires has arisen. The conventional magnetic separators described above have not been able to remove a sufficient amount of the steel wire and thus have been found unsuitable for use in the tire reclaiming industry.